Iranian authorities, including Supreme leader Ayatollah Ali Khamenei, had warned the opposition against turning anti-Israel rallies to street protests against the clerical establishment.

Defeated presidential candidates Mousavi and Mehdi Karoubi said they would attend the rally.

Thousands of supporters of Mousavi, wearing green wristbands or shawls, were among the crowds marching in the "Qods (Jerusalem) Day" rallies held nationwide every year on the last Friday of the Muslim fasting month of Ramadan.

Supporters of hardline Iranian President Mahmoud Ahmadinejad clashed with reformists during anti-Israel rallies on Friday, a witness said.

"Supporters of Ahmadinejad are beating supporters of (opposition leader Mirhossein) Mousavi near the Vali-ye Asr street (in central Tehran). At least two protesters were injured," the witness said.

Iran's June presidential election, which was followed by huge opposition protests, plunged Iran into political turmoil and exposed deepening divisions within its ruling elites.

The opposition leaders say the poll was rigged to secure Ahmadinejad's re-election. The authorities deny it.